Resinous compositions and plasticizers therefor



hatented Apr. 23, was

stares-parent anemone cosmosmons sun asser WES MRWGE @harlee C. tllark,Kenmore, N. Y The Mathieson Alkali Works, Inc,

N. Y a corporation of Virginia No Drawing. Application October SerialNo. delimit Many resins and other thermoplastic compo sitions, forexample polystyrene and cellulose acetate, are dimcult to plasticizesatisfactorily. In many instances plasticizers that are suitable forother resins or thermoplastic compositions are ineffective orincompatible wit polystyrene, cellulose acetate and the like;

As the result of my investigations, I have discovered that substantiallyall resins and thermoplastic compositions such as the above mentionedcellulose esters and especially resin and cellulose esters that havebeen diflicul. to plasticlze heretofore may be plasticizedsatisiactorily through the l addition of relatively small proportions ofall phatlc esters of halogen-bearing polycarbomlic acid. My plasticizersare efl'ective not only with the resins and cellulose esters per se, butin other plastic compositions containing resins and cellu lose esters,such for example, as lacquers.

Although small amounts of my plasticizers are effective, they arecompatible in large proportions with resins and cellulose esters whichhave been difllcult to plasticlze heretofore. Thus, my plasticizers may.be combined in relatively large proportions with polystyrene andpolymers of substituted styrenes such as poly-methylstyrene,poly-chlorostyrene,' poly-dichlorostyrene and, the like. Moreover,cellulose esters, such as the acetate, propionate, butyrate, benzoateand mixtures of these esters-(for example, cellulose acetatebutyrate)are greatly improved through the additerials and particularly syntheticresins may be plasticized with aliphatic esters of halogenated aromaticpolycarboxylic acids to yield in fllm or in bulk form plastics that aretougher, harder and longer lived and at the same time less brittle thanplastics derived from similar resinswith heretofore customaryplasticizers. Moreover, the plastior to jYork,

cizer of my invention are particularly desirable in that there is notendency for them to separate from the plastic composition eitherupon-polymerization or after polymerization and long standing.

To consider the plasticizers in somewhat greater detail, it should benoted that they are esters of halogenated aromatic polycarboxylic acidsbearing carboiwl groups directly on the aromatic ring or rings, the term"polycarboxylic acid" being employed to include those having two or morecarboxylic acid groups.

Polycarboxylic acids or anhydrldes which, 'afterhalogenation andesterlflcation, are suitable for the practice of my invention includephthalic, isophthalic, terephthalic, trimesic, pyromellitlc, naphthalicand the like. alkyl, aryl or other groups in such acids also pro.-

duces compounds, for example the diphenic acids,

fiuorenone dicarboxvlic acids and the like'which may be halogenated andesterifled and employed in the practice of my invention.

Generally speaking, the monocyclic acids (after halogenation and.esteriilcation) produce preferred plasticizers.

' Although the invention is described hereinafter with particularreference to chlorine-bearing substitution products of aromaticpolycarboxylic acids, it will be understood that other halogens may beemployed. Preferred plasticizers for the practice of my inventionusually contain two or more halogen atoms per molecule, although onlytion of my plasticizers and yield improved bulk plastics and films. e Inshort, a great variety of thermoplastic maone such halogen addition maybe sufliclent in some instances.

I have found that it is advantageous in many instances to use mixturesof the aliphatic esters oi halogen bearing aromatic polycarboxylic acidsrather than the pure compounds, since in this way I obtain liquids orlow-melting solids that, as plasticizers, are preferable tohighermelting compositions. By way of example, a preferred plastlcizerprepared in accordance with my invention' comprises a mixture of ethylchlorophthalates containing 2 to 3 chlorine atoms per molecule, say anaverage of about 2.4 atoms of chlorine per molecule;

In the formation of the esters from the acids various aliphatic alcoholsmay be employed, the

- lower alcohols containing not more than six carbon atoms beingpreferred. It is advantageous in the esterificatlon to employ primary orsecondary alcohols, although the alcohol chains may be branched orstraight. Among the plasticizers presently preferred are those preparedfrom .55 ethyl, propyl, butyl and amyl alcohols.

The substitution of 'The plasticizers may be synthesized in variousways. By way of example, a suitable plasticizer may be prepared bychlorinating phthalic anhydride in fuming sulfuric acid using a trace ofiodine as a catalyst. The chlorination is continued until about 2.4atoms of chlorine per molecule have been absorbed. Thereafter the chlorinated phthalic anhydride is esterified by ethanol, while passingthrough the mass a catalyst in the form of hydrogen chloride gas. Theesteriiied product is purified by washing, drying and distillation toproduce a composition that i has a melting point of 88-90 F. and whichcrystallizes only very slowly after melting. Other aliphatic esters ofhalogenated phthalic army-=- 62,846, filed October 21, 1942, anhydrousferric.

chloride may beemployed as the sole halogenat- Esteriflcation of thechlorinated phthalic anhydride thereafter is conducted as describedabove.

However prepared, the esters of halogenated poiybasic acids employed asplasticizers preferably should bear halogen on the ring because in suchcase they are more stable, so stable-in fact that they do not evolvehydrohalogen acid on standing.

Other methods of preparing the ester plasticizers of my invention may beemployed. For example phthalic anhydride may be esterifled prior tochlorination, provided that care is taken in the latter step tointroduce halogen on the ring only.

It will be clear, of course, that other derivatives of phthalic acid maybe ring halogenated and subsequentl converted into esters.

To consider-my invention in somewhat greater detail, attention isdirected to the following examples:

EXAMPLE 1 Diethyl and diamyi esters, respectively, of dichlorophthalicacids were mixed in various proportions with four differentthermoplastics, namely, cellulose acetate, polystyrene, methylmethacrylate and cellulose nitrate. The plasticizing effect, in eachinstance, is shown in the following ing agent. In such case, the ferricchloride is table in comparison with samples of the resin more than acatalyst, since it is used in stoichiwhich contain no plasticizers.

' Dichlorophthalate Dlethyl ester, percent Diamyl ester, percent Remittit 10 to 10 25 so Cellulose mtate B lmeu; Somewhat brittle. Flexible.Polystyrene Tfmgh Somewhat brittle. Somewhat brittle. Sticky Tossingthan Tougher than Sticky. Metbylmetbacrylate.. Hard Rubbe "L. Rubbery.Cellulose nitrate do ticky Sticky.

ometric quantities and gives up its chlorine to the EXAMPLE 2 aromaticring. In such a haiogenation operation,

Parts of FeCl: re-

quired perv 148 parts (1 mole) of phthalio anhydride Atoms of Clintroduced per mole of phthalic anhydride By way of example, phthalicanhydride may be chlorinated as follows: I

. Chlorine gas is passed over heated coarse iron filings until the ironis converted into ferric chloride. To 167 parts of the ferric chloridethere is added 88 parts of phthalic anhydride, the resulting mixturebeing fused together and maintained at a temperature just insuiiicientto cause distillation, for 1 hours. Thereafter, the tempera ture israised and the chlorinated phthalic anhydride is distilled out of thereaction mixture.

chlorine gas is not brought into contact with the organic material to behalogenated but is em-' In this case, a coating composition was preparedby dissolving 1 part byweight of polystyrene in 7.7 parts of toluene.This mixture had a viscosity suitable for brushing. To 30.8 parts ofmixture was added 1.3 parts of mixed ethyl esters of ch10- rinatedphthalic acid containing an average of about 2.4 atoms of chlorine permolecule. Similar mixtures were made employing mixed butyl esters ofpolystyrene and toluene was used without any plasticizer.

In each instance, the resulting coating compositions were brushed onto aclean steel test panel which was allowed to dry overnight,-

After drying overnight the following results were observed. The filmcontaining no plasticizer, i. e. derived from the polystyrene andtoluene alone, was very brittle but was not hard and showed only fairadhesion to the steel panel.

The film plasticized with butyl phthalate was plastic rather thanbrittle and was relatively tough, but it did not adhere well to themetal.

The remaining films, all of which were plasticized with the esters ofchlorinated phthalic acid, were harder and tougher than theunplasticired film and adhered much better to the metal than the filmplasticized with butyl phthalate.

The film plastioized with ethyl chlorophthalate was much harder andtougher than any oi the other films. Moreover, it adhered much morestrongly to the metal.

EXAMPLE 3 In this instance, a base solution was prepared by mixing 50parts by weight of cellulose acetate with 52 rts by weight of ethylacetate and 341 parts of acetone. The resulting solution was of his thesame proportions as in the case of the butyi phthaiate-L3 parts ofchloroesters to 35.4 parts solution. a

In all-instances, the resulting coating compositions were brushed ontometal test panels and allowed to dry overnight. After drying thefollowing resultswere observed. 'l'he unplasticized him was hard andbrittle. The film plasticized with butyl phthalate was less brittle andconsiderably softer than the unplasticized iilm and did not adhere wellto the metal. The films plasticized with the chloroesters were superiorand were less brittle and more plastic than theother films and adheredmore strongly to the metal.

The film plasticiud with the ethyl esters of the chlorophthalic acidgave the best film.

Y I 4 The plastlcized blends of Example 2 were permitted to smnd for sixmonths. Re-examination at the end of this interval showed that thesolvents had evaporated completely. In the case of the unplastlcizedsample oi cellulose acetate, the result was a hazy translucent solid.The cellulese acetate plasticized with butyl phthalate was a hard whiteopaque solid. In all instances. the samples plasticized with thechlorophthalic esters were soft solids or clear viscous liquids.

The blend con a :1. the ethyl ester was particularly desirable and was aclear soft non-tacky solid. Iclalm:

i. A thermoplastic composition from the class consisting of polystyreneresins, methyl methacrylate resins and cellulose esters plasticized witha mixture of alkyl halophthalates obtained by the esteriflcation of alower aliphatic alcohol with phthalic anhydride halogenated until fromtwo to four atoms of halogen have been absorbed per molecule of phthalicanhydride.

2. A thermoplastic composition from the class consisting of polystyreneresins, methyl methacrylatc resins and cellulose esters plasticized witha mixture oi alkyl chlorophthalates obtained by the esteriflcation of alower aliphatic alcohol with phthalic dc chlorinated until trom two tothree atoms of chlorine have been absorbed per molecule of phthalicanhydride.

3. A thermoplastic composition from the class consisting of polystyreneresins, methyl methacrylate resins and cellulose esters plasticized witha mixture of ethyl chlorophthalates obtained by the esterification ofethanol with phthalic anhydride chlorinated until from two to threeatoms of chlorine have been absorbed per molecule of phthalic anhydride.

' 4. A thermoplastic composition from the class consisting ofpolystyrene resins. methyl methacrylate resins and cellulose estersplasticized with a mixture of ethyl chlorophthalates obtained by theesteriiication of ethanol with phthalic anhydride chlorinated until anaverage of about 2.4 atoms of chlorine have been absorbed per moleculeof phthalic anhydride.

5. A polystyrene resin plasticized with a mixture oi almlchlorophthalates obtained by the esterification of a lower aliphaticalcohol with phthalic anhydride chlorinated until from two to threeatoms of chlorine have been absorbed per molecule of phthalic anhydride.

6. A polystyrene resin plasticized with a mixture of ethylchlorophthalates obtained by the esteriflcation of ethanol with phthalicanhydride chlorinated until from two to three atoms of chlorine havebeen absorbed per molecule of phthalic anhydride. 1

7. A polystyrene resin plasticized with a mixture of ethylchlorophthalates obtained by the esteritlcation of ethanol with phthalicanhydride chlorinated until an average of about 2.4 atoms of chlorinehave been absorbed per molecule of phthalic anhydride.

8. A cellulose ester plasticized with a mixture oi alkylchlorophthalates obtained by the esteriflcation of a lower aliphaticalcohol with phthalic anhydride chlorinated until 'irom two to threeatoms of chlorine have been absorbed per molecule oi phthalic anhydride.

9. A cellulose ester plasticized with a mixture of ethylchlorophthalates obtained by the esterification of ethanol with.phthalic anhydrlde chlorinated until from two to three atoms ofchlorine have been absorbed per molecule of phthalic anhydride.

10.- A cellulose ester plasticized with a mixture of ethylchlorophthalates obtained by the esteriiication of ethanol with phthalicanhydride chlorinated until an average of about 2.4 atoms of chlorinehave been absorbed per molecule 01 phthalic anhydride.

11. A polymerized dichlorostyrene plasticized with a mixture or ethylchlorophthalates obtained by the esteriflcation 01' ethanol wlthphthalicanhydride chlorinated until irom two to three atoms of chlorine havebeen absorbed per molecule of phthalic anhydride.

